Low-stress TSV design using conductive particles
A component can include a substrate having a first surface and a second surface remote therefrom, an opening extending in a direction between the first and second surfaces, and a conductive via extending within the opening. The substrate can have a CTE less than 10 ppm/° C. The conductive via can include a plurality of base particles each including a first region of a first metal substantially covered by a layer of a second metal different from the first metal. The base particles can be metallurgically joined together and the second metal layers of the particles can be at least partially diffused into the first regions. The conductive via can include voids interspersed between the joined base particles. The voids can occupy 10% or more of a volume of the conductive via.
1. A method of fabricating a component, comprising:
providing a substrate having a first surface and a second surface remote therefrom, the substrate having a CTE less than 10 ppm/° C., the substrate having an opening extending from the first surface towards the second surface;
depositing a plurality of base particles into the opening, each base particle including a first metal region and a second metal layer covering the first metal region, the second metal layer having a melting point below 400° C., the first metal region having a melting point of 500° C. or more, at least some of the base particles further including a non-metal core region surrounded by the first metal region; and
heating the base particles so that each second metal layer fuses the base particles to one another to form a continuous conductive via extending within the opening.
2. A method as claimed in claim 1 , wherein the substrate embodies a plurality of active semiconductor devices adjacent the second surface, and the conductive via is electrically connected with at least one of a plurality of conductive elements at the second surface.
3. A method as claimed in claim 1 , further comprising, after the step of heating the base particles, planarizing the first surface.
4. A method as claimed in claim 1 , further comprising depositing a polymer medium into at least some of the voids interspersed between the joined base particles, the polymer medium extending at least to a penetration depth from at least one of the first and second surfaces within the opening.
5. A method as claimed in claim 1 , further comprising depositing solder into at least some of the voids interspersed between the joined base particles, the solder extending at least to a penetration depth from at least one of the first and second surfaces within the opening.
6. A method as claimed in claim 1 , wherein each first metal region is a metal selected from the group consisting of: copper, nickel, aluminum, and tungsten, and an alloy including copper.
7. A method as claimed in claim 1 , wherein each second metal layer is a metal selected from the group consisting of: tin, bismuth, indium, cadmium, selenium, zinc, and alloys thereof.
8. A method of fabricating a component, comprising:
providing a substrate having a first surface and a second surface remote therefrom, the substrate having a CTE less than 10 ppm/° C., the substrate having an opening extending from the first surface towards the second surface;
depositing a plurality of base particles into the opening, each base particle including a first metal region and a second metal layer covering the first metal region, the second metal layer having a melting point below 400° C., the first metal region having a melting point of 500° C. or more; and
heating the base particles so that each second metal layer fuses the base particles to one another to form a continuous conductive via extending within the opening,
wherein each base particle includes a barrier layer between the first metal region and the second metal layer.
9. A method as claimed in claim 1 , wherein the base particles are provided in a liquid carrier material.
10. A method as claimed in claim 9 , wherein the step of depositing the base particles into the opening is performed by dispensing, inkjet printing, laser printing, screen printing, or stenciling.
11. A method as claimed in claim 9 , wherein the liquid carrier material evaporates as a result of the heating step.
12. A method as claimed in claim 9 , wherein the liquid carrier material includes a fluxing component.
13. A method as claimed in claim 12 , further comprising, during or after the heating step, performing a vacuum treatment to remove the fluxing component.
14. A method of fabricating a component, comprising:
providing a substrate having a first surface and a second surface remote therefrom, the substrate having a CTE less than 10 ppm/° C., the substrate having an opening extending from the first surface towards the second surface;
depositing a plurality of base particles into the opening, each base particle including a first metal region and a second metal layer covering the first metal region, the second metal layer having a melting point below 400° C., the first metal region having a melting point of 500° C. or more; and
heating the base particles so that each second metal layer fuses the base particles to one another to form a continuous conductive via extending within the opening,
wherein the second metal layer is a bi-metal layer covering the first metal region, and the step of heating heats the base particles to a transient liquid phase reaction temperature, each second bi-metal layer forming a eutectic low melt around the first metal region, and
wherein each second bi-metal layer includes a layer of tin and a layer of an alloy including a metal selected from the group consisting of: silver, copper, indium, zinc, and bismuth.
15. A method as claimed in claim 14 , wherein the eutectic low melt of at least some adjacent ones of the base particles diffuses into the first metal regions of the adjacent base particles.
16. A method as claimed in claim 1 , wherein the opening defines an inner surface extending from the first surface toward the second surface, further comprising, before forming the conductive via, depositing an insulating dielectric layer coating the inner surface.
17. A method as claimed in claim 16 , further comprising, before forming the conductive via, forming a third metal layer overlying the dielectric layer and lining the opening.
18. A method as claimed in claim 17 , wherein the step of forming the conductive via metallurgically joins at least some of the base particles with the third metal layer.
19. A method as claimed in claim 1 , wherein the step of depositing the base particles into the opening includes depositing a mixture of the base particles and interstitial particles into the opening, the interstitial particles being incorporated into the structure of the conductive via.
20. A method as claimed in claim 19 , wherein at least some of the interstitial particles are third metal particles.
21. A method as claimed in claim 20 , wherein the interstitial particles include at least one metal selected from the group consisting of: silver, gold, tungsten, molybdenum, and nickel.
22. A method as claimed in claim 19 , wherein at least some of the interstitial particles have a non-metal core region, the non-metal selected from the group consisting of: silica, ceramic, graphite, and polymer.
23. A method as claimed in claim 1 , wherein each non-metal core region is a material selected from the group consisting of: silica, ceramic, graphite, and polymer.